About time I get a diesel - PeachParts Mercedes-Benz Forum

cth350 · #1 05-04-2008, 10:37 AM

Having owned well over 100 mercedes in various shapes and sizes, all gas, in the past 20 years (most were parts cars), I have a good handle on vintage mercedes technology.

In the past few months, I have acquired a pair of OM617a turbo diesel parts cars. I've been trying to sell one motor without much success (see the parts forum). Having a second motor is just "too much".

So, what do I need to do to put this 2nd motor into a 380slc? The donor is a W123 sedan.

- Exhaust from the diesel car is single pipe. The 380slc is dual. Sounds like a custom job.
- Engine mounts hopefully just line up. If not, I'll fiddle with the size and shape of the aluminum arms that hold everything down.
- Ignition wiring is clearly different. But what particulars about the switch setup do I need to know? Beyond the presence of the vacuum cut-off.
- Operational engine wiring, like the glow-plug circuit and the fuel pump circuit.
- Same fuel tank? Is there an insert in the filler for the diesel to take a narrower nozzle? (or vice versa)
- With luck, the drive shaft length will be "close enough" or I can find another one to doctor.

Anything else?

Thx -CTH

300SDog · #2 05-05-2008, 02:23 AM

Final drive gear ratio compatiability would be something to consider. If the SLC is 2.88 it'll be too tall. Can recollect the 107 carried the m110 twincam 6cyl in SL configuration and thats good news, bein an engine shared with 123's. Thus oughta be no prob with sump clearance of subframe. Also reconnoitre clearance for high mounted 617 oil filter to steering gear and brake servo. Wheelbase of the SLC should tell ye alot, is it wide like 116's?? If so that's very good news. Heck, the 116 is the *only* chassis that accomodated virtually every engine MB made.

Otherwise the 617 will include different engine mounts that include engine shocks. You got the handle on glow plug relay and vacuum/solenoid fuel cut-off plus GP wiring to key switch. No doubt wanna swap the entire key switch and hookups. The rest will mostly involve boning the SLC of no longer needed electrical hookups. There aint no electrical governance of diesel injection pump and zero ignition as you know. The only electrics involved in diesels are just the GP system, alternator and starter motor.

(edit: Rule is that converting from gasoline to diesel is easy, its the opposite thats near-impossible. And diesel is probly the last frontier for Vintage MB fans, it was for me.

#3 05-05-2008, 02:31 AM

Quote:

Originally Posted by cth350

So, what do I need to do to put this 2nd motor into a 380slc?

A new hood, the engine is too tall.

t walgamuth · #4 05-05-2008, 02:35 AM

the rear should be 247 which will yield very good fuel economy with liesurely acceleration. there may be interference on the sump, though, but i am pretty sure this has been done before so it must be solvable.

good luck

tom w

pawoSD · #5 05-05-2008, 07:02 AM

Quote:

Originally Posted by ForcedInduction

A new hood, the engine is too tall.

I thought someone has done an SEC....which has a very similar hood height to the SL....I bet it would work without a taller hood or any hood modifications...

t walgamuth · #6 05-05-2008, 07:39 AM

Quote:

Originally Posted by pawoSD

I thought someone has done an SEC....which has a very similar hood height to the SL....I bet it would work without a taller hood or any hood modifications...

Well, yes. a 617 will go where a 110 gasser goes and that was offered in the 107s.

Tom W

Mister Byrnzoil · #7 05-05-2008, 07:41 AM

new hood or hood scoop..

http://www.peachparts.com/shopforum/showthread.php?t=216498

vstech · #8 05-05-2008, 08:24 AM

I have seen two that did not require any external modifications. the SLC 107 frame will handle the 617.

cth350 · #9 05-05-2008, 08:52 AM

Valve cover clearance was something I was worried about. Am not going to do anything to the car that isn't reversable, since it's not worth that kind of engineering. Heck, I'd put a 6.9 in if casual welding was an option.

Thx guys. I'll test fit the motor later this week and see what happens.

-CTH

cth350 · #10 05-07-2008, 07:04 AM

somebody else asking the same question...
http://www.biodieselnow.com/forums/t/17094.aspx

-CTH

cth350 · #11 05-18-2008, 02:54 PM

nope, it don't fit. I have some interference problems with the rubber flex disk I left on the transmission interfering with the flex disk left on the driveshaft (not exactly a bright thing to do), but heck, it's only a test fit in the engine compartment for now.

There's a good 3" between the back of the valve cover and the firewall, so theoretically I can shift the engine back a bit more than it is. At present, the oil pan sits over the axle instead of inside the well for it, and the engine mounts are significantly behind where the aluminum support arms are.

There' are a few inches here and there that can be cleaned up, but the oil pan is just not happy down below, and the rocker cover clearly sticks up over the line for the hood.

I had an oilpan from a 280SL that went with the motor to friend that was fixing a car. So I'm in no position to figure out if I can swap out this oilpan for something more suitable.

However, swapping the oil pan won't get me the kind of clearance I need to get the rocker cover and the air cleaner under the hood.

There are modications that can be made to the car to get more room (starting with spaces for the subframe to lower it's position under the hood. But they require rather substantial changes to the steering and it's not worth doing. If I were trying to shoehorn a 6.9 under the hood, perhaps the heavy changes might be justified to somebody that wants to drive really fast. But this project was undertaken solely because I find myself with an extra motor and a car that needs one.

Oh well. Anybody need a 300D motor with about 225,000 miles on it? It belonged to another forum member, who sold the car because he had been hit in the rear some time back and finally had to reclaim the parking space. The car ran well onto the trailer I used to get it home; starting on the first turn of the key.

Time to post another thread in the for-sale column.

Thx -CTH

TheDon · #12 05-18-2008, 04:08 PM

I don't think its a great time to buy a diesel...

#13 05-18-2008, 04:12 PM

Its always time for a Diesel.

cth350 · #14 05-19-2008, 08:05 AM

Well, lets just say that getting a diesel at this point would have been easy, if it fit.
Of course, I also have a 500sec and 300se/c that need motors, but putting a diesel in them wasn't what I had in mind.

The 300b adenaur sedan I just picked up is the other candiate for a diesel, since it too came without a motor. But it also came without a driveshaft, fuel tank, transmission and a few other bits. The original 6 cylinder gas motor with three carbs produced 125hp. The OM617a also produced 125hp (but that's an apples to orange comparison based on the change in measuring techinique).

-CTH